Improve int64 coercion behaviour (#206)

Co-authored-by: Davis Vaughan <davis@rstudio.com>

R/num_equal.R

@@ -11,15 +11,14 @@ num_equal <- function(x, y, tolerance = default_tol()) {
   }
 
   if (is_int64(x) || is_int64(y)) {
-    in_range <-
-      (!is.double(x) || all((x >= 2^63 & x <= 2^63 - 1) | is.na(x))) &&
-      (!is.double(y) || all((y >= 2^63 & y <= 2^63 - 1) | is.na(x)))
-    if (isTRUE(in_range)) {
+    if (can_int64(x) && can_int64(y)) {
       x <- bit64::as.integer64(x)
       y <- bit64::as.integer64(y)
     } else {
-      x <- as.double(x)
-      y <- as.double(y)
+      cli::cli_abort(c(
+        "No way to coerce to compatible numeric type.",
+        i = "Try again without setting `tolerance`."
+      ))
     }
   } else {
     attributes(x) <- NULL
@@ -46,3 +45,15 @@ num_equal <- function(x, y, tolerance = default_tol()) {
 
   avg_diff < tolerance
 }
+
+
+can_int64 <- function(x) {
+  if (is.integer(x) || inherits(x, "integer64")) {
+    return(TRUE)
+  }
+
+  # https://yutani.rbind.io/post/savvy-v0.7.1-usize/
+  in_range <- x >= -2^53 & x <= 2^53
+  is_whole <- trunc(x) == x
+  all(in_range, is_whole, na.rm = TRUE)
+}

tests/testthat/_snaps/num_equal.md

@@ -0,0 +1,9 @@
+# can't can't compare large integers
+
+    Code
+      num_equal(9007199254740996, bit64::as.integer64(1))
+    Condition
+      Error in `num_equal()`:
+      ! No way to coerce to compatible numeric type.
+      i Try again without setting `tolerance`.
+

tests/testthat/test-num_equal.R

@@ -37,9 +37,12 @@ test_that("NaN is equal to NA_real_ unless tolerance is NULL", {
   expect_true(num_equal(NA_real_, NA_real_))
 })
 
-test_that("coerce large integers to doubles not int64", {
-  expect_no_warning(num_equal(36893488147419103232, bit64::as.integer64(1)))
-  expect_no_warning(num_equal(bit64::as.integer64(1), 36893488147419103232))
+test_that("can't can't compare large integers", {
+  expect_snapshot(
+    num_equal(9007199254740995, bit64::as.integer64(1)),
+    error = TRUE
+  )
+  expect_false(num_equal(9007199254740991, bit64::as.integer64(1)))
 
   expect_no_error(num_equal(NA, bit64::as.integer64(1)))
   expect_no_error(num_equal(bit64::as.integer64(1), NA))